The climate treaty talks in Durban, South Africa, are confronting some fundamental disagreements among the 190-plus nations represented at the meeting. In addition to the usual divides between rich and poor, and north and south, there is no consensus about the best way to move forward with an international agreement to reduce greenhouse gas emissions.

Confronting that reality, United Nations Secretary General Ban Ki-moon yesterday urged the gathered delegates to press on, even so. Ban admitted up front that a comprehensive deal may well be out of reach in Durban. But that's not reason to give up.

"Yes, we all recognize the realities of our time: the economic crisis, the dictates of fiscal austerity, often difficult domestic politics," he said. "Yet the world, and its people, cannot accept 'No' for an answer in Durban."

Getting to yes, though, doesn't just depend on economic conditions. There's also a fundamental rift between nations. Fourteen years ago in Kyoto, nations attempted to create a treaty from the top down, in which the international community collectively set the targets for reducing emissions.

That paradigm mostly failed. It has largely been replaced with a new approach, which emerged from the Copenhagen climate talks two years ago.

"In a way we are sort of turning the Kyoto model on its head," says Elliot Diringer, the executive vice president of the Center for Climate and Energy Solutions, formerly known as the Pew Center on Global Climate Change. He says many countries in Copenhagen reluctantly accepted an approach in which individual nations would figure out for themselves what they can achieve and then pledge to work toward those goals, with no consequences other than scorn if they fall short.

"Once we have sorted out at home what we are prepared to do, then it is much easier to bring that into the international context, then commit ourselves to that in a binding fashion," Diringer says.

But right now, not everyone shares the desire to turn this arrangement back into a binding international treaty, so it remains a catalog of voluntary actions. And Diringer says many nations still bridle at the system that has largely replaced the Kyoto treaty.

"It's difficult for people to give up what we thought was the answer, and envision a path toward a new answer," he says.

One problem is the new voluntary pledges don't come anywhere close to cutting carbon dioxide emissions enough to stop global warming.

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Bill Hare, from a nonprofit called Climate Analytics in Berlin, says the pledges made last year in Cancun put the world on a track to blow through the internationally agreed upon goal of limiting global warming to 2 degrees Celsius.

"We're heading to well over three degrees," Hare says. "We estimate three and a half degrees if the Cancun pledges are fully implemented, completely. If not, then we're headed for much higher levels of warming."

And Hare says reaching those goals is proving to be a stretch. The United States, for instance, hasn't laid out a clear plan for its pledge to reduce emissions 17 percent from 2005 levels by the end of the decade, and right now it does not appear to be on track to meet it.

"The U.S. is not alone in that context. What we see from emission trends in many countries, is at the very best, countries are slow to introduce the policies to meet their pledges," Hare says.

And some of those pledges, such as China's, aren't even to reduce emissions, but just to slow the rate of increase a bit. Yet the world's major emitters have said they are not planning to consider more ambitious pledges just yet.

Having a legally binding treaty wouldn't solve that problem. But Jennifer Haverkamp from the Environmental Defense Fund argues that it's important to maintain some sort of credible international forum, and that's a potential victim in the battle over a future treaty.

"It's no accident that Australia passed a climate law right before this set of meetings. It's no accident that South Africa came out with a climate policy just a few weeks ago," Haverkamp says. "So this process is still important for catalyzing and encouraging those activities by countries, but we can't put all our eggs in this basket."

Environmental groups realize a lot of the action is now at the state and even local levels, and action, after all, is what counts in the end. So groups are putting additional efforts there, figuring if there's success at smaller scales, it will encourage national governments to make bigger commitments, if they ever do decide to move back into a legally binding international deal.